daf is basically saying 'lets assume that 100% of the material...

daf is basically saying 'lets assume that 100% of the material has no water and no ash in it - what would be the energy then? ie "Dry Ash Free (daf)".

But as you can see 36% of this coal is either water or ash. Consumers are interested in the number as this is the reality of what they purchase.

adb is a real number. it is saying lets leave the coal in the open and a certain amount of water will evaporate from it (coal will dry - ie natural upgrading). What is the energy then even with the ash in it and an eq'brium amount of H20